The Calorie Restriction Diet

Eat, drink, and—if the science is any indication—live a really, really long life.

Jason ZaskyMay 19, 2011

Brian M. Delaney.

It’s a diet that appeals mostly to men, and weight loss is “an unfortunate consequence,” says Brian M. Delaney, 47, president of Calorie Restriction Society International (CRSI), about the calorie restriction (CR) diet. Strictly speaking CR is not a diet plan, but a set of dietary principles that call for a reduction in calorie intake while minimizing empty calories. The goal of CR is to slow—and in some ways reverse—the aging process, with the idea of living 110, 120, even 130 years or longer.

To be sure, research conducted on a wide variety of laboratory animals has demonstrated that CR can increase maximum life span by anywhere from forty to fifty percent. Now the results of human studies—including CALERIE (Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy), and research utilizing CRSI volunteers—are coming in, and indicating that a CE diet does extend life. “[O]bviously the maximum achievable life span of humans on a CR diet has not yet been … determined,” writes Delaney and co-author Lisa Walford in their recent book “The Longevity Diet” (Da Capo Lifelong), which makes the case—to readers and physicians alike—why the diet is worth trying, while also offering practical advice on how to get started.

For his part, the 5'11" Delaney—who is responsible for creating the Usenet discussion group Sci.life-extension in 1993, which subsequently evolved into CRSI (a non-profit which raises funds to support CR research)—has been on some version of the CR diet for almost twenty years, his weight fluctuating between 129 and 139 pounds during that time. Delaney estimates that “a few tens of thousands of individuals worldwide” are on some form of the diet, with at least two- or three-thousand on a “fairly serious” version of it. He spoke with Failure about CR while sipping tea in his Stockholm abode, and freely discussed misconceptions about the diet, as well as the challenges of limiting oneself to just 1,500 or so calories a day.

How is a calorie restriction diet different from a weight loss diet?

It’s different in two ways. One is that it has a fundamentally different goal. The goal has nothing to do with weight loss. It’s really about health and longevity. Weight loss is, for many of us, an unfortunate consequence.

Also, people trying to design a weight loss diet might not end up designing one that is capable of promoting longevity. Some diets that are very controversial—like those that are high in protein or, paradoxically, high in fat—may not promote longevity. But it seems like they do promote weight loss, at least in the short term.

What are the biggest misconceptions about the calorie restriction diet?

One huge misconception is that it’s all or nothing. When it gets presented that way [people think] they have this choice: Eat five thousand calories of junk food [per day] or eat fourteen-hundred calories of rabbit food. The evidence suggests that even a slight reduction [in caloric intake] will confer some health and longevity benefits. It’s a horrifying disservice to the public to suggest that people should consider whether they want to radically change their diet. What they should consider is a slight change, because they can improve their health and feel better and maybe take it a step further later.

Are there more males or females on the diet?

Many more males, a mystery we have not been able to figure out. I think it’s a reflection of the interest in life extension among men, not an interest in dieting.

What is the greatest challenge to staying on the diet?

It’s not the hunger, because the hunger you get used to. For me, and a lot of people I’ve spoken to, it’s the desire to not look so skinny. I don’t eat lunch. That’s how I limit my caloric intake. I eat two normal sized meals—breakfast and dinner. The hunger for me is not a big deal. The reason I’m not on a more extreme version of the diet is that I don’t want to look even skinnier. That’s true for a lot of men I know.

And for some people the social aspect is tricky, though it doesn’t need to be. You can go out to a steak dinner and eat three-thousand calories one day [and make up for it the next]. It’s a problem for people who want to eat an exact number of calories every day, which the research suggests is not necessary.

Might a steak dinner lead to falling off the wagon, so to speak?

Absolutely. Some people get used to this state of being a little bit hungry most of the time and when they eat much more than they normally do it can re-awaken the body to the pleasures of excess.

Do Calorie Restriction Society members enjoy food more, because there is less of it and they put more thought into what they are eating?

Most certainly. Usually people ask the question a different way: “Do members enjoy food less and are thereby able to put up with this horrible diet?” You do experience the pleasure of food in a more intense way, in part because you put more thought into what you eat, but also because you’re a little hungrier.

Do members of the Calorie Restriction Society consider themselves guinea pigs?

In many ways they do feel that way, but it’s not so much a question of whether they feel the diet will be effective. It’s more to what extent it will be effective, because the evidence is strong enough at this point that we’re not worried about having wasted our time. But there is a sense that we are doing an experiment on ourselves. And a lot of us are signed up for new studies on human calorie restriction. Even those who aren’t signed up for studies are weighing themselves and getting their cholesterol levels and fasting glucose levels tested a couple times a year.

What does the latest and greatest research say about the impact of a calorie restriction diet on aging and longevity?

At this point no one who knows the research would say that the diet will not extend lifespan at least a bit. What we don’t know—and this is a key motivational question for a lot of people: Is the percentage gain in lifespan seen in laboratory rats and mice—which is very high, forty or fifty percent—will those percentage gains be seen in humans? It might be that the percentage gains seen in humans—who are already very long-lived and might have mechanisms that make calorie restriction redundant—will be less. The latest research involves pulling muscle tissue from people on the diet and doing a very careful analysis of which genes have been turned on or off. It will be extremely interesting to see how the results compare to the genes that are altered in other organisms on CR.

What should an individual do before embarking on a calorie restriction diet?

Everyone should try to get a good gauge of their current state of health before making any changes. Then you can look back and see what effect the diet has had on you.

What is your motivation for living a really long time?

My motivation has changed. I am less interested in living [a long time] than I used to be. What I like more is the effects of this diet. I wake up and feel young. Then I think, I would like to feel the same way tomorrow. And the following day. That’s what leads to the conclusion that it might not be so horrible to live a really long life. I think for most people, it’s a sense of curiosity about how it’s going to turn out.